This invention relates to a process and apparatus for both (i) quenching a fuel gas mixture including at least one gaseous hydrocarbonaceous foulant (described more particularly hereinbelow) and (ii) removing at least a portion of the foulant without substantial formation of mist thereof in the fuel gas mixture. The invention is especially applicable to treating raw gaseous fuel produced by pressure gasification of coal in a fixed-bed gasifier.
Fixed-bed gasifiers and methods for pressure gasification of coal are described in Woodmansee in U.S. Pat. Nos. 3,811,849 and 4,150,953, which are incorporated herein by reference. The latter patent additionally illustrates a gas clean-up system wherein, as described in the patent," an oily aqueous blowdown liquid or condensate body 118 [in a vessel referred to as a "gas quench unit"] comprising a mixture of water, oil, tar and volatile hydrocarbons is drawn off . . . for recirculation of the quenching liquid . . . to sprayhead 124 [within the gas quench unit]." (col. 7 at lines 7-14). As further described in that patent: "In the quench unit, the sprayed aqueous liquid may be at a temperature of, for example, 330.degree. F., resulting in condensation from the gas of condensible hydrocarbons including tar and volatile hydrocarbons. The resulting oily aqueous blowdown liquid 118 collected in the quench unit contains condensed volatile hydrocarbons and other contaminants removed from the raw gas." (See col. 3 at lines 20-27.)
However, there remains a substantial need in the art for a process and apparatus capable of both quenching a fuel gas mixture including at least one gaseous hydrocarbonaceous foulant (e.g., hydrocarbon oil) and removing at least a portion of the foulant without substantial formation of mist thereof in the gas mixture.
It has now been found, by practice of the present invention, that such need is substantially fulfilled.
The invention is eminently suitable for quenching and clean-up of sulfur-bearing raw fuel gas, such as that produced in pressurized gasification of medium-to-high sulfur coal (as taught, for example, in the above-cited U.S. Pat. No. 4,150,953), to produce treated fuel gas which has such quality and temperature (e.g., 200.degree. F.) that it can be directly introduced into a hot potassium carbonate absorption system for removal of the sulfur as H.sub.2 S. That is, no further treatment of the gas is required, thereby omitting the need for such additional prior art steps as washing (whereby foulant mist is removed), further cooling, etc., and requisite apparatus therefor.